Uber Technologies Inc. said on Tuesday it would partner with car-sharing service Maven, operated by General Motors, to allow Uber drivers to rent GM vehicles on a weekly basis.

The 90-day pilot is a surprise move for Maven and General Motors, which with Lyft -- Uber's main competitor in North America -- announced a program in March called Express Drive used mostly by Lyft drivers. Maven operates in 10 U.S. cities.

After GM invested $500 million in Lyft in January, the Express Drive program was the first initiative to come out of the partnership.

Carmakers are increasingly looking to invest in ride services, concerned over a projected eventual decline in private ownership of vehicles that threatens their core business. Other carmakers that have invested in ride service programs include Ford, Mercedes-Benz maker Daimler and Toyota.

Rachel Holt, Uber's regional general manager for North America and Canada, said the service will operate only in San Francisco for now.

The cost per week is $179 plus taxes and fees, Holt said, with no extra fees if drivers use the car for personal use.

Julia Steyn, GM's vice president of urban mobility, said the pricing for Uber drivers was "at parity" with what Lyft drivers pay, although both companies offer their own incentives.

Lyft spokeswoman Sheila Bryson said Maven's partnership was similar to how Lyft worked with Hertz. Lyft drivers can also use Hertz cars through the Express Drive program.